Guests on the holiday sailings on four Celebrity Cruises ships in the Caribbean will have the chance to attend a concert with pop singer Demi Lovato that is being arranged and sponsored by the cruise line.

The concert will take place in St. Maarten, just outside the port, on Dec. 28. Tickets are available on a first-come, first-serve basis, said Celebrity in a statement.

The concert is available to guests on the following sailings and ships: Dec. 19 Equinox; Dec. 21 Eclipse; Dec. 24 Summit; and Dec. 24 Reflection. All ships will be in port on the same day.

“We always want to offer our guests unforgettable experiences so we’re ecstatic to provide families with the chance to see Demi Lovato perform in concert this holiday season,” said Lisa Lutoff-Perlo, President and CEO, Celebrity Cruises. “We’re also offering a special meet-and-greet with Demi, a truly unique and unforgettable experience that only Celebrity can provide. We can’t think of a better way for families to celebrate the holidays and prepare for the New Year than enjoying a one-of-a-kind concert in St. Maarten combined with a modern luxury cruise. This is what makes us so distinct.”

Lutoff-Perlo continued: “It is incredibly rare to find four ships from our world-class fleet docked together in the same port of call; it’s as if the stars aligned to make this occasion even more special. This once-in-a-lifetime opportunity couldn’t have come at a better time.”